Arkmodel piston tank question

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  • Monahan Steam Models
    Captain
    • Apr 2020
    • 755

    Arkmodel piston tank question

    I recently came across a deal on a Arkmodel piston tank WTC for their type VIIC kits. I already have a MSD for the type VIIC I’m building currently but picked up the Arkmodel wtc for evaluation purposes and possible future Frankenstein Experiments.

    Straight away I noticed the piston tank didn’t function how it seems it should. Well not at all. I suspect there might be an issue with the wiring to the micro limit switches. I checked the schematic that came with the kit but I don’t trust it as I have already found a number of errors in the assembly drawings. I cross referenced the wiring with photos I found on the interwebz and sure enough it wasn’t the same.

    Does anyone have a functioning Arkmodel piston tank set up that can post a photo of how the micro switches are wired? Would like to double check that against what I’m seeing with the setup I have.

    Thanks,

    Nick
  • Subculture
    Admiral
    • Feb 2009
    • 2119

    #2
    Nothing for that particular tank, but they’ll just be limit switches and there’s only a few ways they can be wired depending on what you are using to control the tank motor and whether you want to slot the high or low side.

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    • tifosi12
      Commander
      • Jul 2020
      • 346

      #3
      Originally posted by Monahan Steam Models
      I recently came across a deal on a Arkmodel piston tank WTC for their type VIIC kits. I already have a MSD for the type VIIC I’m building currently but picked up the Arkmodel wtc for evaluation purposes and possible future Frankenstein Experiments.

      Straight away I noticed the piston tank didn’t function how it seems it should. Well not at all. I suspect there might be an issue with the wiring to the micro limit switches. I checked the schematic that came with the kit but I don’t trust it as I have already found a number of errors in the assembly drawings. I cross referenced the wiring with photos I found on the interwebz and sure enough it wasn’t the same.

      Does anyone have a functioning Arkmodel piston tank set up that can post a photo of how the micro switches are wired? Would like to double check that against what I’m seeing with the setup I have.

      Thanks,

      Nick
      Sorry to hear that.

      I've made similar negative experiences with a variety of companies in this hobby. It's like there is no quality control. Put a product out there, test it and deliver it with building instructions. Happens everywhere else (RC cars, RC planes, RC boats). So disappointing. Just recently I took another vendor off my list for a product that lacks, well pretty much everything.

      Comment

      • Subculture
        Admiral
        • Feb 2009
        • 2119

        #4
        Click image for larger version

Name:	piston3.jpg
Views:	308
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ID:	146595Click image for larger version  Name:	piston2.jpg Views:	0 Size:	65.9 KB ID:	146592

        Click image for larger version  Name:	piston tank.jpg Views:	0 Size:	21.8 KB ID:	146593
        Last edited by Subculture; 01-11-2021, 12:59 PM.

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        • Monahan Steam Models
          Captain
          • Apr 2020
          • 755

          #5
          Thanks guys for your replies.

          UPDATE: managed to get it sorted out this morning. Piston tank is functioning properly now. The wiring was incorrect and the wiring diagram included with the BCU is incorrect.

          Comment

          • trout
            Admiral
            • Jul 2011
            • 3545

            #6
            Andy, who's piston tank board is that you are sharing?
            If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

            Comment

            • Subculture
              Admiral
              • Feb 2009
              • 2119

              #7
              That's one of Norbert's boards.

              Comment

              • trout
                Admiral
                • Jul 2011
                • 3545

                #8
                Do you like his boards?
                If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

                Comment

                • Subculture
                  Admiral
                  • Feb 2009
                  • 2119

                  #9
                  I prefer transistorised boards. Markus Rieger are good, but pricey, not sure about present availability. Pololu do some nice servo boards. You can also use servo amplifier boards for smaller tanks (about 50mm 2" diameter).

                  Comment

                  • trout
                    Admiral
                    • Jul 2011
                    • 3545

                    #10
                    What is Markus website address?
                    If you can cut, drill, saw, hit things and swear a lot, you're well on the way to building a working model sub.

                    Comment

                    • Monahan Steam Models
                      Captain
                      • Apr 2020
                      • 755

                      #11
                      Andy and Tom,

                      Great info you’re sharing. Thank you!

                      Comment

                      • Subculture
                        Admiral
                        • Feb 2009
                        • 2119

                        #12
                        Markus never had a website. I can probably dig out an email address when I go home, but it’ll be an old one as I haven’t from him for years, so don’t know if it’ll work, or he may not even be making them anymore.

                        Comment

                        • Monahan Steam Models
                          Captain
                          • Apr 2020
                          • 755

                          #13
                          Messing around with the Arkmodels wtc, the two supplied molded end pieces of the wtc appear to suffer from mold shift during the casting process. The concentricity from the inner form to the outer form are shifted to port. Due to the nature of these parts designs and the way the assembly of parts go together, this casting shift seriously effects alignment, function and sealing of critical parts.

                          Assembling the end caps per the limited instructions with the casting shift yielded excessive friction on the drive motors output shafts as well as the linear seals of the servo shaft linkage penetrations to the point of failure.

                          Overall the original design concept was acceptably carried out but the precise manufacturing of the parts defeated the original intent.



                          Now how to fix all of this...Making custard out of cow $h@! is what’s to follow.

                          Comment

                          • Subculture
                            Admiral
                            • Feb 2009
                            • 2119

                            #14
                            Often the case with Chinese manufactured goods.. Poor quality control during construction combined with poor quality materials. The design is usually fine, because it tends to be derivative or a blatant copy.

                            Comment

                            • Monahan Steam Models
                              Captain
                              • Apr 2020
                              • 755

                              #15
                              Seems who ever the company farmed out the injection molding of the end caps to, is the one at fault for quality control. Would be curious to know if Arkmodel is even aware of the issue?

                              The pushrod penetrations are a good design. They use an oil-lite bushing with a u-cup seal. Unfortunately the counter bores that hold each of these components are significantly misaligned due to the casting shift. I also found that the bores were intended to be collinear to the central axis of the wtc but instead are crooked.

                              The fix for the pushrod penetrations should be easy enough by vertically mounting the end caps on a milling machine and boring the penetrations out a little oversized to correct the misalignment and crookedness. A cartridge can then be turned on a lathe to hold the oil-lite bushing and cup seal. Then this assembly can be inserted and sealed into the newly oversized penetration bores.

                              A similar repair can be made to the motor shaft penetrations but will require possibly a new seal solution as the u-cup seals provided in the kit are the same for the pushrods and were intended for 2mm shafts, not the 2.3mm shafts that the motors have.



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